The goal of the Clinical Core (Core C) is to provide centralized expertise and capacity to enroll well-characterized cohorts of participants infected with M. tuberculosis to meet the aims of the TBRU. Coordination by the Clinical Core will create internal consistency across cohorts and improve the efficiency of enrollment for the TBRU projects involving human subjects, as well as for TBRU Collaborative Projects. Subjects will be enrolled at two highly experienced and established sites: the Kenya Medical Research Institute (KEMRI) / U.S. Centers for Disease Control and Prevention (CDC), in Nyanza Province, and at the DeKalb County Board of Health in Atlanta, Georgia. Infrastructure at these sites for conducting TB clinical and translational studies is among the best in the world. Since 2007, the KEMRI TB Branch has enrolled over 28,000 adults and children into research studies, including 8,000 followed in longitudinal cohorts. The BSL3 TB research laboratory has state-of-the-art capacity for mycobacteriology, immunology, specimen archiving and international shipping. KEMRI/CDC conducts ongoing population-based, active surveillance for infectious diseases that will be leveraged for TBRU studies. The DeKalb/Atlanta site has collaborated with Emory and CDC in TB research for over a decade. More than 2,500 newly arrived refugees from high-burden TB countries are seen annually and over 1,500 adults with LTBI are identified and offered treatment each year. Data management, quality assurance and regulatory procedures in Kenya and Atlanta are of the highest quality, making these exceptional sites to achieve TBRU Project aims. The Clinical Core will be a major resource for the TBRU by providing: 1) expertise in clinical and translational research that spans more than a decade and includes over 15 TB endemic settings; 2) coordination of participant enrollment and follow-up to achieve maximal efficiency and synergy between projects; 3) centralized specimen collection, processing and shipping through the TBRU Data Management Center; and 4) assurance of high-quality, ethical research conducted in accordance with U.S. and international regulatory requirements.